Petrogenetic Insights and Volcanic Hazards in the Springerville Volcanic Field: A Comparative Study of Blue Ridge Mountain and Coyote Hills Shield Volcanoes

Students: Loet Van Hoven, Jackson Kaiser

Faculty Mentor: Marissa Mnich

Geology

College of Science, Technology, and Business

The Springerville Volcanic Field (SVF), located in eastern Arizona on the southern edge of the Colorado Plateau, is one of the largest volcanic fields in the U.S. It hosts over 450 cinder cones and two significant polygenetic shield volcanoes—Blue Ridge Mountain to the west and Coyote Hills to the east. These volcanoes provide insights into the region's eruptive and petrogenetic history, contrasting with the more common monogenetic volcanism in the area. Recent dating suggests that the youngest lava flows are less than 50,000 years old, which is more recent than previously thought. Additionally, a newly discovered tuff unit at the base of Coyote Hills points to potentially explosive volcanic hazards not previously recognized in the field. The Blue Ridge Mountain area, located on the western side of the field, has been thoroughly mapped, revealing 21 volcanic units. These basaltic units show variations in mineralogy, texture, and flow morphology, despite similar major and trace element geochemistry. Thin section analyses of the lava samples have revealed disequilibrium textures, such as sieve-textured plagioclase and pyroxene reaction rims on xenocrystic quartz, suggesting complex magmatic processes like magma mixing or recharge. A key feature of these lava flows is the presence of large olivine and plagioclase glomerocrysts, up to 1 cm in size. Coyote Hills shares similarities with Blue Ridge Mountain, and preliminary mapping and sampling suggest comparable magmatic processes, though their full extent is still under investigation.